THE CYANOBACTERIAL FLORA OF MICROBIOTIC CRUSTS OF NATURAL BRIDGES NATIONAL MONUMENT, UTAH

Abstract

Nagy, M. L. & Johansen, J. R.Department of Biology, John Carroll University, University Heights, OH 44118 USAWe examined the cyanobacterial flora of microbiotic crusts in two sites of Natural Bridges national Monument. Composite soil samples were subsampled, dilution plated on Z8 media, and incubated 3‐5 weeks. Cyanobacteria were characterized directly from plates, and isolations were made of all morphologically distinct strains. The cyanobacterial flora of soils of this site differed markedly from cyanobacterial floras observed elsewhere in the soils of the Colorado Plateau. Oscillatoriales were well represented, with Leptolyngbya (4 spp.), Microcoleus (3 spp.), Schizothrix calcicola, Phormidium rubroterricola, and Oscillatoria coerulescens all present. Coccoid cyanobacteria were notably absent, and heterocystous species were limited in number (only Scytonema javanicum and Calothrix elenkinii) and very rare. Nostoc species were unusually rare, and seen only in moistened soil samples. Tolypothrix was also seen in the moistened soils. Two especially interesting strains are likely new taxa. A Schizothrix morphospecies was recovered with distinctively constricted cells and a yellow‐brown calyptra that fits no description of Schizothrix or Leptolyngbya. An especially large form of Microcoleus vaginatus was found with a trichome width of 5‐9.6 m. Sequence of the 16S rRNA provides some evidence that both of these morphospecies may be distinct from other members in their genera.